The invention relates to plastic well screens and end fittings therefor. Plastic well screens are typically made by wrapping a plastic wire around a series of longitudinal plastic support rods to which the wire is ultrasonically welded. Typically, the threaded end fittings which permit threaded pipe to be attached to the well screens are of substantially greater diameter than the well screens and have internally shouldered recesses in one end into which an axial portion of the screen is inserted and retained by solvent welding. The use of large diameter fittings requires the use of well casing which is substantially larger in diameter than the well screen, and thus quite costly both in material and the labor to drill the well. Alternatively, for a given casing diameter, a substantially smaller diameter well screen must be used where a large diameter fitting must be accommodated.
Plastic well screens made of PVC are often preferred for use in ground water monitoring well applications since they provide good corrosion resistance at low cost. However, the solvents typically used to attach PVC fittings and pipe to PVC screens can leach out and possibly contaminate the ground water that is being monitored, thus detracting from the usefulness of the well.
It is known that certain metal parts can be butt welded to each other by spinning one part relative to another to develop sufficient friction heat to fuse the parts together. However, it would appear that an attempt to butt weld a length of plastic well screen to a tubular plastic fitting would provide a joint which would probably be very weak.